Author: Lauren Bishop

Mortality is a valuable measure of population health. Mortality statistics are often used to assess the burden of disease within a certain population, as well as trends and changes in the disease burden over time.

Mortality is commonly reported as a rate, though the standard rates differ in terms of the population under study.

Here are some frequently used measures of mortality:

Crude mortality rate	The number of deaths during a specific time interval divided by the total number of individuals at risk of dying during that time interval.
Cause-specific mortality rate	The number of deaths attributed to a given cause during a specific time interval divided by the total number of individuals at risk of dying during that time interval.
Age-specific mortality rate	The number of deaths among individuals in a certain age group during a specific time interval divided by the total number of individuals at risk of dying in the age group during that time interval.
Infant mortality rate	The number of deaths among children < 1 year old divided by the total number of live births during that time interval.
Maternal mortality rate	The number of deaths attributed to pregnancy- or childbirth-related causes during a specific time interval divided by the total number of live births during that time interval.

Note Mortality may also be reported in terms of risk ratios and odds ratios, which are discussed in more detail in Risks and odds.

Note Since the denominator in, e.g., the crude mortality rate does not include the time at risk, some epidemiologists would argue that it is not a true rate. It should also be noted that the denominator in mortality rates based on vital statistics, such as the number of death certificates, often reflects the size of the population as of the middle of the time interval, rather than at the beginning of the time interval (i.e. the incidence proportion).